Because it's not worth the hours when it inevitably breaks, which corpo server setups always do. At least in my view, that is. If it's running GNU/Linux or, God forbid, Windows, honestly as the head of a larger company I can just make a guy or another company fix it asap, whereas with BSD you'll be reliant on a handful of people at the very most, and no one is going to help you. They'll help you to help yourself, but 2 hours spent on something where I could've just called up another big company and have them do it, is a waste of money. Also whilst Linux can update without reboot (I believe you even do kernel updates now?), as far as I know BSD is a lot more fond of rebooting. BSD as a whole is more turbulent and uncoordinated than GNU/Linux, honestly. It's the individual distros up against each other that makes BSD the more stable party, i.e BSD vs Debian. But sometimes, being coordinated and calm just means "not innovative". BSD is probably the furthest you can get from progress and innovation imo.